1. Field of the Invention
The invention relates to captive panel fastener assemblies; and, more particularly, to an improved fastener assembly for aircraft for holding the head and shank of the bolt of the fastener assembly away from an aperture in a panel of the aircraft in a first position while permitting the bolt to be pushed to a second position where the head abuts against the aircraft and the shank enters the aperture in the aircraft and may be threaded to a receptacle assembly mounted to a substructure.
2. Description of the Prior Art
Panel fasteners for aircraft are well known. Usually, such fasteners secure a panel to an aircraft by insertion through an opening in the aircraft panel and a nut attached to the panel on the blind side is threaded to the shaft of the fastener, the enlarged head abutting against the panel on the access side thereof. Means have been suggested in the prior art for preventing the fastener from becoming disengaged from the panel when the fastener is threaded out of engagement with the nut. For example, in U.S. Pat. No. 4,069,855 to Petroshanoff, the fastener is captivated to the panel by a retaining ring which includes integral tabs that ride within crosschannels and an installation slot extending intermediate the ends of the fastener. However, in this arrangement, the ring eats or bites into the threads of the shank wearing out the same and destroying its utility. It may then have to be drilled out of the panel aperture resulting in lost man hours.
In U.S. Pat. No. 4,464,090 to John A. Duran, commonly assigned, there is disclosed an improved captive panel fastener which can hold the head and shank of the fastener to the panel prior to installation while permitting pushing of the head and shank into the aperture to engage a nut without damaging the threads of the shank.
In the invention disclosed in U.S. Pat. No. 4,464,090, a captive panel fastener is provided having an enlarged head and a threaded shank with a pair of slots extending longitudinally along the outer periphery of said shank through the threads thereof. A C-shaped ring is trapped in a grommet assembly and has a pair of inwardly extending ends riding in the slots. In this manner, when the grommet assembly is installed in an aperture, such as in the skin of an aircraft panel, the fastener can be pushed between positions whereby, in a first position, the grommet assembly and C-ring are at one end of the shank holding the head and shank outwardly from the aircraft panel, and, in a second position, the C-ring rides along the slots and abuts against the head so that the remaining threaded shaft can extend through the aperture with a nut threaded thereon securing the fastener to the panel.
The shaft of the fastener in U.S. Pat. No. 4,464,090 is externally threaded. However, there is a need in the aircraft industry for captive panel fasteners having shafts with either internal threads or stepped or tapered bodies. Further, in U.S. Pat. No. 4,464,090, the fit of the C-ring in the groove of the shaft and the grommet is such that a certain amount of play is present. There is a need for a captive panel fastener which can hold the head and shank thereof, which shank may be tapered or straight, or internally or externally threaded, away from an aperture in an aircraft panel or the like, prior to installation, in a firm stable manner. This would result in good retention of the C-ring in the fastener with little play between the grommet assembly and the shaft resulting in maximum engagement and strength.